tools/net/Makefile: Define PACKAGE to fix build problems

Fixes the following build problem with binutils-2.24

gcc -Wall -O2   -c -o bpf_jit_disasm.o bpf_jit_disasm.c
In file included from bpf_jit_disasm.c:25:0:
/usr/include/bfd.h:35:2: error: #error config.h must be included
before this header
 #error config.h must be included before this header

This is similar to commit 3ce711a6
"perf tools: bfd.h/libbfd detection fails with recent binutils"

See: https://sourceware.org/bugzilla/show_bug.cgi?id=14243



CC: David S. Miller <davem@davemloft.net>
CC: Daniel Borkmann <dborkman@redhat.com>
CC: netdev@vger.kernel.org
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Signed-off-by: Markos Chandras <markos.chandras@imgtec.com>
Signed-off-by: David S. Miller <davem@davemloft.net>